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CN-122000630-A - Battery diaphragm, preparation method thereof and lithium ion battery

CN122000630ACN 122000630 ACN122000630 ACN 122000630ACN-122000630-A

Abstract

The application relates to the technical field of lithium ion batteries, in particular to a battery diaphragm, a preparation method thereof and a lithium ion battery, wherein the battery diaphragm comprises a flexible film substrate, and a ceramic coating and a polydopamine coating which are sequentially arranged on the surface of the film substrate from inside to outside. According to the technical scheme, the ceramic coating and the polydopamine coating are compounded on the membrane substrate, so that the electrolyte affinity and the thermal stability of the battery diaphragm can be effectively improved, and the electrochemical performance and the use safety of the battery can be improved.

Inventors

  • JIANG LINLIN
  • XIE JIAN
  • Qin Xuekai
  • CHEN ZHENYU
  • Hu Junchang

Assignees

  • 上汽通用五菱汽车股份有限公司

Dates

Publication Date
20260508
Application Date
20251230

Claims (10)

  1. 1. The battery diaphragm is characterized by comprising a flexible film substrate, and a ceramic coating and a polydopamine coating which are sequentially arranged on the surface of the film substrate from inside to outside.
  2. 2. The battery separator of claim 1, wherein the ceramic coating comprises one or more of aluminum oxide, zirconium oxide, silicon oxide, cerium oxide, magnesium oxide, barium sulfate, barium titanate.
  3. 3. The battery separator according to claim 1, wherein the ceramic coating layer is an alumina layer, the alumina layer includes first particles and second particles, the first particles are alumina particles having a particle diameter of less than 0.1 μm, the second particles are alumina particles having a particle diameter of 0.1 μm to 1.0 μm, and the mass content of the first particles in the alumina layer is 10% to 40%, and the mass content of the second particles is 50% to 80%.
  4. 4. The battery separator of claim 3, wherein the first particles have a particle size D1 and the second particles have a particle size D2, D1/d2 = 0.10-0.20.
  5. 5. The battery separator of claim 1 wherein the film substrate comprises one or more materials of polyethylene, polypropylene, polyvinylidene fluoride, polyimide.
  6. 6. The battery separator as in any of claims 1-5, wherein the ceramic coating has a thickness of no more than 2.5 μm and/or, The thickness of the polydopamine coating is not more than 2.5 μm.
  7. 7. A method of preparing the battery separator according to any one of claims 1 to 6, comprising the steps of: providing a flexible film substrate, and arranging a ceramic coating on the film substrate; And setting a polydopamine coating on the surface of the ceramic coating.
  8. 8. The method according to claim 7, wherein the step of providing a ceramic coating layer on the film substrate comprises preparing a ceramic coating liquid, coating the ceramic coating liquid on the surface of the film substrate, drying, and forming a ceramic coating layer on the film substrate, and the method further comprises at least one of the following features (1) - (4): (1) The ceramic coating liquid comprises ceramic materials, a binder and a wetting agent, wherein the ceramic materials comprise one or more of aluminum oxide, zirconium oxide, silicon oxide, cerium oxide, magnesium oxide, barium sulfate and barium titanate; (2) The ceramic coating liquid comprises ceramic materials, wherein the ceramic materials comprise first particles and second particles, the first particles are alumina particles with the particle size smaller than 0.1 mu m, the second particles are alumina particles with the particle size of 0.1 mu m to 1.0 mu m, the mass content of the first particles in the ceramic materials is 10% -40%, and the mass content of the second particles is 50% -80%; (3) The ceramic coating liquid comprises ceramic materials, a binder and a wetting agent, wherein the binder in the ceramic coating liquid accounts for 8-12 wt% of the total solid content of the ceramic coating liquid; (4) The ceramic coating liquid comprises ceramic materials, a binder and a wetting agent, wherein the wetting agent accounts for 0.05-0.15 wt% of the total solid content of the ceramic coating liquid.
  9. 9. The method of claim 7, wherein the step of disposing a polydopamine coating on the surface of the ceramic coating comprises: dissolving a pre-measured dopamine monomer in Tris buffer solution with pH of 8.5-8.8 to form dopamine coating liquid with preset concentration; And placing the membrane matrix provided with the ceramic coating in the dopamine coating liquid, carrying out oscillation reaction on a constant-temperature shaking table, washing and drying, and forming a polydopamine coating on the surface of the ceramic coating.
  10. 10. A lithium ion battery comprising a battery separator according to any one of claims 1-6.

Description

Battery diaphragm, preparation method thereof and lithium ion battery Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a battery diaphragm, a preparation method thereof and a lithium ion battery. Background In recent years, with the gradual development of new energy industries, lithium ion batteries have been widely used in consumer electronics, new energy automobiles, energy storage systems and industrial fields. Lithium ion battery safety has been a major concern in the battery development process. The lithium ion battery is composed of a positive electrode, a negative electrode, an electrolyte solution and a diaphragm. The separator serves as a key component in the battery and has the two functions of isolating the positive electrode from the negative electrode and preventing the battery from being short-circuited and providing a migration channel for lithium ions. There are many studies to improve the safety of lithium ion batteries by modifying lithium ion battery separators. Lithium ion battery separators used in the industry are typically polyolefin microporous membranes, which have certain cost advantages and basic electrode isolation functions. However, this type of membrane has two disadvantages. Firstly, the separator itself shows insufficient electrolyte wettability and interfacial compatibility due to lack of polar groups, and secondly, the separator has low melting point (130-140 ℃) and is flammable and has poor thermal stability. Therefore, there is a need to improve electrolyte affinity and thermal stability of battery separators for developing safe and reliable lithium ion batteries. Disclosure of Invention The application provides a battery diaphragm, a preparation method thereof and a lithium ion battery, and aims to improve the affinity and thermal stability of electrolyte of the battery diaphragm. In a first aspect, an embodiment of the application provides a battery separator, which comprises a flexible membrane substrate, and a ceramic coating and a polydopamine coating which are sequentially arranged on the surface of the membrane substrate from inside to outside. In some embodiments, the ceramic coating comprises one or more materials of alumina, zirconia, silica, ceria, magnesia, barium sulfate, barium titanate. In some embodiments, the ceramic coating is an alumina layer comprising first particles and second particles, the first particles being alumina particles having a particle size of less than 0.1 μm, the second particles being alumina particles having a particle size of 0.1 μm to 1.0 μm, the mass content of the first particles in the alumina layer being 10% to 40% and the mass content of the second particles being 50% to 80%. In some embodiments, the first particles have a particle size D1, and the second particles have a particle size D2, where d1/d2=0.10 to 0.20. In some embodiments, the film substrate comprises one or more materials of polyethylene, polypropylene, polyvinylidene fluoride, polyimide. In some embodiments, the ceramic coating has a thickness of no more than 2.5 μm. In some embodiments, the polydopamine coating has a thickness of no more than 2.5 μm. In a second aspect, an embodiment of the present application provides a method for preparing a battery separator according to the first aspect, including the following steps: providing a flexible film substrate, and arranging a ceramic coating on the film substrate; And setting a polydopamine coating on the surface of the ceramic coating. In some embodiments, the step of disposing a ceramic coating on the film substrate includes preparing a ceramic coating liquid, coating the ceramic coating liquid on the surface of the film substrate, drying, forming a ceramic coating on the film substrate, the ceramic coating liquid including a ceramic material including one or more of alumina, zirconia, silica, ceria, magnesia, barium sulfate, and barium titanate, a binder, and a wetting agent. In some embodiments, the ceramic coating liquid includes a ceramic material including first particles and second particles, the first particles are alumina particles with a particle size of less than 0.1 μm, the second particles are alumina particles with a particle size of 0.1 μm to 1.0 μm, and in the ceramic material, the mass content of the first particles is 10% -40%, and the mass content of the second particles is 50% -80%. In some embodiments, the ceramic coating liquid comprises ceramic materials, a binder and a wetting agent, wherein the binder accounts for 8-12 wt% of the total solid content of the ceramic coating liquid. In some embodiments, the ceramic coating liquid comprises ceramic materials, a binder and a wetting agent, wherein the wetting agent accounts for 0.05-0.15 wt% of the total solid content of the ceramic coating liquid. In some embodiments, the step of disposing a polydopamine coating on the ceramic coating surface comprises: dissolving a pre-measured dopamin